Enhanced dark adsorption and visible-light-driven photocatalytic properties of narrower-band-gap Cu2S decorated Cu2O nanocomposites for efficient removal of organic pollutants Publication date: 15 February 2020 Source: Journal of Hazardous Materials, Volume 384 Author(s): Yamei Yue, Pengxin Zhang, Wei Wang, Yuncheng Cai, Fatang Tan, Xinyun Wang, Xueliang Qiao, Po Keung Wong Abstract The Cu2S-decorated Cu2O nanocomposites were synthesized by a facile co-precipitation and calcination method, and used as adsorbent and photocatalyst to remove organic pollutants from wastewater. Batch adsorption experiments were conducted to investigate the influences of molar ratio of Cu2O to Cu2S, initial solution pH, coexisting anion and temperature on the adsorption performances. As-obtained Cu2O/Cu2S-9/1 nanocomposite with high specific surface area (45.88 m2/g) exhibited superior adsorption ability towards Congo red, methyl orange and tetracycline in aqueous solution. The adsorption of organics onto the nanocomposite was a spontaneous and exothermic process, and the adsorption processes could be well described by the Freundlich isothermic and Pseudo-second-order kinetic models. The Cu2O/Cu2S-9/1 nanocomposite also showed excellent photocatalytic degradation activities for organic pollutants. Optical properties characterization suggested that the decoration of Cu2S could effectively enhance visible-light absorption and inhibit the recombination of photo-generated electron-hole pairs. ESR tests and trapping experiments of reactive species indicated that both superoxide radicals (O2−) and holes (h+) were crucial for the photocatalytic degradation of organic pollutants. Moreover, the photocatalytic efficiency of Cu2O/Cu2S-9/1 nanocomposite had no significant decrease even after four consecutive runs. The bifunctional nanocomposite as adsorbent and photocatalyst presents a great potential in treating organic-contaminated wastewater. Graphical abstract

Tuning tetracycline removal from aqueous solution onto activated 2:1 layered clay mineral: Characterization, sorption and mechanistic studies Publication date: 15 February 2020 Source: Journal of Hazardous Materials, Volume 384 Author(s): Ali Maged, Jibran Iqbal, Sherif Kharbish, Ismael Sayed Ismael, Amit Bhatnagar Abstract Water pollution due to emerging contaminants (especially pharmaceuticals) is a major environmental threat which results in the development of antibiotic-resistant bacteria/resistance genes in the aquatic environment. Therefore, robust and cost-effective methods are required to address this problem. In this study, thermal activation was opted for the modification of natural bentonite clay (BC) and utilized to investigate the adsorptive removal of tetracycline (TC) from aqueous solution. The physicochemical surface properties of the raw and modified bentonite samples were also investigated. The BET analysis revealed that the thermally activated bentonite (TB) has better properties than BC. The surface area of TB was found to be more than two-fold higher compared to that of BC. The FTIR spectra exhibited the existence of AlOH, SiO and SiOSi functional groups in the samples, confirming the presence of hydrated aluminosilicate in the clay. The effects of various operating parameters were analyzed via optimization studies. The maximum monolayer adsorption capacity estimated by Langmuir model was found to be 156.7 and 388.1 mg g−1 for BC and TB, respectively. Furthermore, fixed-bed column studies were performed to get insights into the adsorption behavior of TB in a dynamic system. The mechanism of TC adsorption by TB was successfully explored. Graphical abstract

Effect of aging on adsorption behavior of polystyrene microplastics for pharmaceuticals: Adsorption mechanism and role of aging intermediates Publication date: 15 February 2020 Source: Journal of Hazardous Materials, Volume 384 Author(s): Peng Liu, Kun Lu, Jinli Li, Xiaowei Wu, Li Qian, Mengjie Wang, Shixiang Gao Abstract In the environment, aging obviously changes physicochemical properties of microplastics (MPs), but the effects of aging process on adsorption behavior of MPs are not fully understood. In this study, the aging of polystyrene (PS) was accelerated by photo-Fenton reaction. The adsorption mechanism of different aged PS toward atorvastatin (ATV) and amlodipine (AML) and the role of PS-derived intermediates in adsorption process were investigated. Results showed that the adsorption of pristine PS toward pharmaceuticals relied on hydrophobic and π-π interaction, while for aged PS, electrostatic interaction and hydrogen bonding controlled the adsorption. The study revealed that the intermediates released from aging process in high concentration (TOC of 10 mg/L) significantly decreased the adsorption of ATV (10 mg/L) on PS (5.0 g/L) but increased the adsorption of AML (10 mg/L). However, those intermediates at environmental concentration (0.1 mg/L) exhibited low effects on adsorption of pharmaceuticals (1.0 mg/L) on MPs (0.5 g/L of PS). The impact mainly depended on electrostatic interaction between MPs and aging intermediates. Besides, the adsorption of low-degree aged PS was more susceptible to the aging intermediates than that of high-degree aged ones. These findings highlight significant implication of MP-derived intermediates in aquatic environments. Graphical abstract

Advanced evaluation of landfill leachate treatments by low and high-resolution mass spectrometry focusing on microcontaminant removal Publication date: 15 February 2020 Source: Journal of Hazardous Materials, Volume 384 Author(s): A. Ruiz-Delgado, P. Plaza-Bolaños, I. Oller, S. Malato, A. Agüera Abstract Conventional wastewater treatments are not usually effective in the remediation of specific landfill leachates due to their high content in toxic and recalcitrant compounds. Advanced and intensive treatments are needed for the decontamination and possible recycling of these effluents. Here, the combination of advanced oxidation processes (solar photo-Fenton) and an aerobic biological reactor have been applied to treat urban landfill leachates. The effectiveness of the proposed treatment line was also evaluated considering the removal of organic microcontaminants (OMCs) identified in the different phases, which is an innovative practice. The analytical strategy included: (i) a target approach (115 analytes) by liquid chromatography-mass spectrometry (LC–MS/MS); and two suspect approaches using (ii) LC-high-resolution MS (database with >1300 compounds) and (iii) gas-chromatography-MS (database with >900 compounds). OMCs on the treated landfill leachate was reduced up to 94% of the initial concentration. 8 target compounds (mainly pharmaceuticals) out of 115 target analytes represented 85% of the OMC concentration in the raw leachate: cotinine, diclofenac, gabapentin, ketoprofen, lidocaine, mecoprop, nicotine and trigonelline. 3 non-previously reported OMCs were confirmed: di-n-nonyl phthalate, o-phenylphenol and tonalide. Leachate partially oxidized by solar photo-Fenton process can be successfully incorporated to biological systems to complete the treatment by means of specifically adapted biomass. Graphical abstract

Controllable incorporation of oxygen in MoS2 for efficient adsorption of Hg2+ in aqueous solutions Publication date: 15 February 2020 Source: Journal of Hazardous Materials, Volume 384 Author(s): Weiquan Zhan, Feifei Jia, Yuan Yuan, Chang Liu, Kaige Sun, Bingqiao Yang, Shaoxian Song Abstract Molybdenum disulfide (MoS2) was incorporated controllably by oxygen in order to modify the hydrophobic surfaces and thus to improve the adsorption of Hg2+ on MoS2 in aqueous solutions in this work. The experimental results indicated that the incorporation of oxygen could dramatically improve the adsorption of Hg2+ on MoS2. With 11% oxygen atom incorporation, the adsorption rate and capacity increased over 17 times and 21 folds, respectively, compared with that without oxygen incorporation. This vast improvement was found to be contributed to that the incorporation of oxygen would greatly enhance the complexation between S atoms and Hg2+ on MoS2 surfaces, resulting in the great increase of the Hg2+ adsorption. The increase of the adsorption capacity with increasing incorporated oxygen reached a plateau, which might be due to the saturation of covalent bond. In addition, the incorporation of oxygen atom greatly enhanced the hydrophilicity of MoS2 surfaces, facilitating the hydrated Hg2+ ions to approach to MoS2 surfaces. This finding might provide a highly potential adsorbent for efficiently removing Hg2+ from water. Graphical abstract

Accumulation and bioavailability of heavy metals in an acid soil and their uptake by paddy rice under continuous application of chicken and swine manure Publication date: 15 February 2020 Source: Journal of Hazardous Materials, Volume 384 Author(s): Yanan Wan, Qingqing Huang, Qi Wang, Yao Yu, Dechun Su, Yuhui Qiao, Huafen Li Abstract Heavy metal contamination of agricultural soils is a global concern, as it can cause the accumulation of heavy metals in food. In this study, a field experiment was carried out to investigate the effect of the continuous application of chicken or swine manure on the Pb, Cd, Cr and As bioavailability, fractionation, and accumulation in soil and uptake by rice plants. Results showed that chicken or swine manure significantly reduced the Cd and Pb contents in rice grain by 7.8–79.3% and 7.2–59.4%, respectively, with increasing application rates and number of years; the exchangeable Cd and Pb fractions, and the diethylenetriaminepentaacetic acid (DTPA)-extractable Cd and Pb in the soil were also decreased. Furthermore, the application of chicken or swine manure substantially increased the DTPA-extractable As and exchangeable As fractions in the soil but had limited effect on As accumulation in rice grain. No significant differences in the bioavailability in soil nor accumulation in the rice grain were found for Cr between the treatments. Therefore, livestock manure can be used as soil amendments to decrease Cd and Pb accumulation in rice grains, nevertheless, the potential risk of metal accumulation in soils caused by livestock manure application should be considered.

Ethanol-activated granular aerogel as efficient adsorbent for persistent organic pollutants from real leachate and hospital wastewater Publication date: 15 February 2020 Source: Journal of Hazardous Materials, Volume 384 Author(s): V. Lakshmi Prasanna, Hadas Mamane, Vinod Kumar Vadivel, Dror Avisar Abstract Hydrophobic aerogels were used to remove three types of persistent organic pollutants: pharmaceutical drugs (i.e. doxorubicin [DOX], paclitaxel [TAX]), phthalates (diethyl phthalate [DEP]), and hydrophilic rhodamine dye (RhB) from synthetic and real wastewaters, using Lumira granular aerogel from Cabot activated with EtOH (ET-GAG). The hydrophobic silica aerogel was characterized by X-ray diffraction (XRD), High-Resolution Transmission Electron Microscopy (HRTEM), Brunauer–Emmet–Teller (BET) and attenuated total reflection–Fourier transform infrared spectroscopy. The pollutants were analysed by high-performance liquid chromatography (HPLC)–UV and HPLC–mass spectrometry. The adsorption process was governed by hydrophobic- hydrophobic interactions between the ET-GAG and micropollutants. The adsorption capacity of ET-GAG, examined by batch experiments, for DOX, TAX and DEP were 13.80, 14.28 and 17.54 mg/g respectively. The rate of adsorption to ET-GAG is high in the initial 40 min followed by no change in the rate due to saturation of adsorption sites. ET-GAG was able to completely remove micropollutants from real leachate and hospital wastewater, implying practical applications. Regeneration of the aerogel was studied by solvent extraction. Et-GAG adsorbent demonstrated better removal of toxic chemotherapeutic drugs and phthalates than GAC. Graphical abstract

Mechanism and performance of singlet oxygen dominated peroxymonosulfate activation on CoOOH nanoparticles for 2,4-dichlorophenol degradation in water Publication date: 15 February 2020 Source: Journal of Hazardous Materials, Volume 384 Author(s): Qihui Zhang, Dan He, Xinran Li, Wei Feng, Cong Lyu, Yifeng Zhang Abstract Peroxymonosulfate (PMS) has gained attention as oxidant for SR-AOPs. It is essential to develop a stable heterogeneous catalyst with strong hydrophilicity and high electron transfer capability for PMS activating. In this study, cobalt oxyhydroxide (CoOOH) was synthesized and activated PMS for degradation of 2,4-dichlorophenol (2,4-DCP) aiming to assess the feasibility of CoOOH/PMS system. 50 mg/L of 2,4-DCP could be 100% degraded within 120 min with 0.20 g/L CoOOH and 6 mM PMS. CoOOH/PMS system possessed a high degradation efficiency (0.0462 min−1), which was about 10 and 4 times higher than Co3O4/PMS and CoFe2O4/PMS system, respectively. Furthermore, it was found that CoOOH/PMS system displayed effective catalytic performance over broad pH range (e.g. 3–9). Importantly, the quenching tests revealed that 1O2 was identified as dominant reactive oxygen species (ROS). Co (Ⅲ) was rapidly reduced to Co (Ⅱ) owing to the efficient electron transfer rate performance of CoOOH in the catalytic reaction. Then, the regeneration of Co (Ⅱ) facilitated CoOH+ owing to the surface of CoOOH with sufficient hydroxyl group, which is crucial for PMS activation and reactive oxygen species-ROS generation. This study proposed an alternative technology based on peroxymonosulfate catalyzed by cobalt-based hydroxide for waste water treatment. Graphical abstract

The effects of thiosulfinates on methane production from anaerobic co-digestion of waste activated sludge and food waste and mitigate method Publication date: 15 February 2020 Source: Journal of Hazardous Materials, Volume 384 Author(s): Ziletao Tao, Dongbo Wang, Fubing Yao, Xiaoding Huang, You Wu, Mingting Du, Zhuo Chen, Hongxue An, Xiaoming Li, Qi Yang Abstract Thiosulfinates, a natural antibiotic, existed in all parts of Allium, therefore might be accumulated in large amounts in food waste (FW). FW was often added into waste activated sludge (WAS) anaerobic digestion process as a kind of supplement for nutrition balance. However, the impact of thiosulfinates on methane production and the possible approach to mitigate its inhibition on the co-digestion process could be available in few literatures. This work was carried out in a series of batch experiment at pH 7.0 ± 0.2 and 35 ± 1.0 ℃ to promote the further understanding of this process. The experimental results showed that the methane accumulation decreased from 270.6 ± 13.4 to 16.7 ± 7.0 mL/g VSS (volatile suspended solids) when the initial concentration of thiosulfinates increased from 0 to 2.5 μg/g VSS. The activities of functional enzymes (F420 and CoM) were inhibited by 99.06% and 99.82% compared with control group when reactor contained 2.5 μg/g VSS thiosulfinates. Furthermore, different temperature, pH, and combination pretreat were applied to impair the inhibition of thiosulfinate. Compared with no pretreatment group, methane yield was increased by 2.26, 32.18 and 42.2-fold, respectively which group was under pretreatment method of heat (100 ℃), alkali (pH 9) and combination. Graphical abstract

Distribution and speciation of iron in Fe-modified biochars and its application in removal of As(V), As(III), Cr(VI), and Hg(II): An X-ray absorption study Publication date: 15 February 2020 Source: Journal of Hazardous Materials, Volume 384 Author(s): Yu Feng, Peng Liu, Yanxin Wang, Y. Zou Finfrock, Xianjun Xie, Chunli Su, Na Liu, Yanyuan Yang, Yong Xu Abstract Characterization of the spatial distribution and speciation of iron (Fe) in Fe-modified biochars is critical for understanding the mechanisms of contaminant removal. Here, synchrotron-based techniques were applied to characterize the spatial distribution and speciation of Fe in biochars modified by FeCl3 or FeSO4 and pyrolyzed at 300, 600, and 900 °C, respectively. Confocal micro-X-ray fluorescence imaging (CMXRFI) results indicated Fe, sulfur (S), and chlorine (Cl) diffused into the basic porous structure of the biochars and aggregated to the surface as pyrolysis temperature increased. Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra revealed maghemite (γ-Fe2O3) as the primary Fe species in the modified biochars and Fe(0) was observed when pyrolyzed at 600 or 900 °C. Unmodified and FeCl3-modified biochars pyrolyzed at 900 °C were evaluated in the removal of arsenate (As(V)), arsenite (As(III)), hexavalent chromium (Cr(VI)) and Hg(II) from aqueous solution and Fe-modification enhanced the removal efficiency from 42.0%, 62.5%, 19.6%, and 97.0%, respectively, to all 99.9%. X-ray absorption spectroscopy results indicate both adsorption and redox reaction contributed to the removal mechanisms. The present study provides a prospective and sustainable material and offers information relevant to tailoring Fe-modified biochars to specific environmental applications. Graphical abstract